os x partition goes missing wtf is wrong

i opened up my macbook, and it wouldn't wake up i did a restart by holding down the power button and it restarted while i held option but in the screen that came up it only showed the one windows partition and there is no option for os x partition. i don't think i've done anythign wrong. i need to know wats going on

yteah i did that and my partition had been renamed from "macbook HD" to something like "drive2dk..." i ran repair and just got some message in red that said it fialed so i just reformated and reinstalled os x for the 5th time since i got my macbook

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